Facsimile apparatus



May 30, 1944. M. AR'rz-r 2,350,003

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INVENTOR May 30, 1944.- M. ARTzT FACSIMILE APPARATUS Filed July 30, 1942 FFM/5 as/r/o/v 2 Sheets-Sheet 2 Cows/05Min 520W.

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nA'I.'TORNEY Patented May 30, 1944 FACSIMILE APPARATUS Maurice Amt, madonnela, N. J., assigner u Radio Corporation of America, a corporation of.

Application July 30, 1942, Serial No. 452,871

20 Claims.

.This invention'relates to an improvement in facsimile receivers and more particularly to a system Vfor maintaining a facsimile receiving apparatus in synchronous operation with the operation oi the facsimile transmitter.

At the facsimile transmitting apparatus the copy to be transmitted is positioned in a machine or transmitter such that the copy can be scanned in a line-by-line fashionl to produce facsimile signals. These signals are then transmitted to the receiver by any appropriate means and are then utilized to' produce a facsimile of the original copy. Naturally, it is necessary to maintain synchronous operation between the transmitter and the one or more receivers in order that a' truecopy of the original may be produced. For thisv purpose it is generally customary to transmit a synchronizing or framing signal at the end of each. line scanned at the transmitter, this signal being generally transmitted to the receivers by the same method utilized for the transmission of facsimile. signals. This synchronizing or framing impulse is then utilized at the receiver for maintaining the receiver in synchronous op-V eration with the transmitter.

Various' methods have been devised for maintaining synchronous operation between the facsimile receiverk and the transmitter. However.

many of the prior art systems are not fully adequate and do not produce the required degree of synchronous operation especially where high speedfac'simile is used. Furthermore, in other known synchronizing systems, the reception ofa synchronizingor framing'signalis necessary to maintain proper operation oi' the receiver with 5 the result that the absence of one or more synchronizing `or framing impulses in* succession may often cause the facsimile receiver to drop completely out of synchronism with the transmitter. The absence of one or more synchro- 'nizing or framing impulses may frequently occur for various reasons such as, for examplefading or a momentary inoperativecondition of a part of the system. Various other known facsimile synchronizing systems have the objection that, 4in the absence' of a synchronizing or framing signal, the receiver may immediately begin to run too fast or too slow and cause a distortion in the produced copy. Furthermore, in other known synchronizing systems the synchronizing or framing impulse is eifective to control the speed ofoperation of the facsimile receiver only during the intervals thatthe synchronizing signal is being received, the machine or-receiver u1 rate with the then lack o! synchronizin.' Such a running "free" between synchronizing intervals.

(ci. 11s-eas) 5 all of the above referred to objections have been overcome and through the use of the present vinvention it is possible to maintain very'accurate synchronism between al facsimile receiver and transmitter even under conditions of fading o l0 or momentary absence ofithe synchronizing or framing impulses. Furthermore, through the use of the present invention'it is possible to produce and maintain a correction voltage for adjusting the speed of operation of the facsimile receiver l5. until the operating speed has been adjusted to bring the operation of the receiver'in synchronismwith the transmitter.

` The present invention utilizes a Wheatstone bridge arrangement with means responsive to 20 received framing impulses for producing a speed correcting voltage, the magnitude of the produced voltage, as well as its polarity, representing the error -in lack of synchronism and whether or not the receiver is operating fast or slow. When 25 the facsimile receiver is in synchronism with the transmitter no correcting voltage is produced, but when the receiver is operating slow with respect to the transmitter a correcting voltage of one polarity is produced. with the magnitude of 30 the voltage being a function of the lack of synchronism, whereas when the receiver is operating fast a voltage oi the opposite polarity is produced in a magnitude which is also a function of the degree of lack of synchronism.

The present invention also includes means for producinga "second order" correction and adding such correction voltage to the original correction voltage thereby improving the operation of the facsimile receiver. Theoretically, complete i0 and absolute correction for maintaining absolute -synchronism between transmitter and receiver would onlybe Possible by using an infinite series` y of corrections. However, it has been `found that the use or the first and second order correction of the series is suiilcient to maintain wholly edequate synchronous operation.

First order correction is a condition in which,

- the correction voltage is produced at each synchronizing or framing interval, the circuit ar- 5o rangement being such that the correction voltage entirely disappears-before (preferably Just before) the next synchronizing or framing interval arrives. If the receiveris still out oi synchronism a new correction voltage is produced commensuconditions of phase and synchronism.

chronism at that time land the new voltage is.

then used to correct for the lack of synchronism,

,. this voltage or a portion thereof being maintained y throughout the entire scanned line.

A certain predetermined voltage may, therefore, be maintained to assure synchronous operation of the receiver and the system'is. therefore, asymptotic to synchronous speed.

It is, therefore, one purpose of the present invention to provide a new and improved synchronizing systemfor use in a facsimile receiver casacca The system shown in Figure 1 responds to short synchronizing or framing impulses received from the transmitter, generally in the form of short tone signals which are transmitted at the start oi each scanned line. Actually the synchronizing or framing signals may be sent more irequently than ior each line ii more accurate syn-v chronizing is desired.

The system includes input transformer it having input terminals i2 connected to the primary thereof. A wave form, such as shown at ld, is to be applied to the terminals i2, and as shown in Figure 1, the wave form i5 comprises a series of short tone signals identical to or corresponding to the synchronizing signals transmitted by the facsimile transmitter.

A full wave rectifier tube it is provided having a cathode and a pair of anodes. The ends of the secondary winding of the transformer I0 are conwhereby the receiver may be maintained in accurate synchronism with the transmitter.

Another purpose of the present inventionresides in the provision of a circuit arrangement whereby a correction voltage is developed at the facsimile receiver, the correction voltage being suitable for assuring or maintaining synchronous operation of the receiver with the transmitter.

Still another purpose of the present invention resides in the provision of means for producing a correction voltage being determined in accordance with whether the receiver is operating fast or slow with respect to the transmitter.

A still further purpose of the present invention resides in the provision oi means at a facsimile receiver responsive to synchronizing or framing impulses for producing a correction voltage, the intensity of the correction voltage being determined in accordance with the lack of synchrotransmitter.

Another purpose 'of the present invention resides in the provision of means whereby the produced correction voltage, or a portion thereof, may be maintained throughout each succeeding scanned linel in order to assure more accurate svnchronism between the receiver and transmitter.

A still further purpose of the present invention resides in the provision of means for 'producingA both ilrst and'second order correction voltages for maintaining synchronous operation between the receiver and the transmitter.

Various other purposes and advantages of the present invention will become more apparent to those skilled in the art from the following detailed description and claims, particularly when considered in commotion with the drawings, wherein Figure 1 represents schematically one form ci the present invention; and

Figure 2 shows 'a plurality of curves representing produced correction voltages under various Referring now to Figure 1, there is shown a bridge network which operates to compare the phase of received synchronizing or framing signals to the phase of operation'of the local recorder or receiver to thereby produce a positive or negative voltage output which represents in polarity and amplitude the error found'to be present. This produced voltage may then be used to bring about or produce the desired synchronous `operation of the receiver.

dit

lnism between' the facsimile receiverl and the y nected to the anodes of the full wave rectiiler tube so that when a synchronizing tone signal is received and applied to the rectier tube It a voltage will be developed across the load resistance It and the condenser 2G connected in parallel therewith. The produced voltage impulses are then applied to a discharge tube 22 having a cathode, a control electrode and an anode. The potentials are naturally applied between cathode and control electrode, and since the cathode of the rectifier It and the cathode of the tube 22 are connected together, synchronizing or framing impulses produce a negative voltage impulse upon the control electrode of tube 22. While this voltage is sufciently negative to bias tube 22 to cause plate current cut-od', it will, however, be apparent that in the absence of a negative impulse or framing signal the tube 22 draws a certain amount of plate current. Tube 22 conditions the bridge for operation to indicate phase displacement and to thereby produce a correction voltage so that when no negative impulse is applied to the grid of tube 22 (as, for example, under abnormal conditions) the bridge is rendered inop-'f erative and no correction voltage is produced.

The four arms of the Wheatstone bridge are represented by tubes 2d and 2B and resistances 28 and 3Q. Each of the tubes 24 and 28 include a cathode, a control electrode and an anode. The tubes 2d and 26 are connected in series with the anode of tube 2t connected to the cathode of tube 253.

A source of potential (not shown) is provided. the positive terminal of the source of potential being connected to terminal 32, while the negative terminal of the source of potential is connected to terminal 3s. Between terminals 32 and 35i are `serially connected resistances 28. and 3G, as well as an additional resistance 36. The cathode of tube 2.5 is connected to the junction of resistances 28 and 36 by way of adjustable resistance 38, while the anode of tube 26 is conv nected to the positive terminal 32 by resistance du, which may be made adjustable if desired.

single helix is used) by cooperation of the helix 'Reissue Patent No.

with the usual printer bar, (not shown) but illustrated in relation to the helix for instance by 20,152, dated October 27, 1936,

granted to cheriee J. Young. The printer drum 42 carries a conducting segment 44 which ex `tends preferably 18o degrees around the drum and a cooperating brush contact 46 is arranged to cooperate with the conducting segment. 'I'he conducting segment 44 and the brush 46 considcathode and an anode. The cathode is connected to the controlelectrode 4of tube 26 by grid bias resistor 6 0 and to the Junction of resistances 36 and-28 by a time constant circuit including parallel resistance 62 and condenser '64. The

anode of tube 46 is connected to the positive terminal l2 by resistance 66 and the anode oi' this tube is also connected to the anode of tube 22 -by resistance 66. 'I'he anode of tube'22 is connecte'd to the control electrode ,of tube 44 by the grid bias resistor; 66. i

The output voltage developed by the bridge is, therefore, available from the junction of resistancs 28 and 36 and from the conductor con-v necting the .anode of tube 24 to the cathode of tube 26. A condenser 62 is connected between these points and the condenser 62 has connected in parallel therewith a series combination including resistance 64 and condenser 66. The resistance 64 is actually the resistance elementoi a potentiometer including movable contact 68. The

' output terminals for the control circuit are indicated at 41li and l2, the former being connected to the adjustable contact 68 and the latter being connected to the Junction of the resistances 26 and 20.

For preferred operation .of the system it is necessary that the bridge -be balanced so that when both tubes 24 and 26 are conducting and are drawing maximum permissible plate current (with the c ommutator closed) no voltage will be developed across the condenser 62. 'I'his balanced condition may be brought about by an adjustment of resistance 36 (or by an adjustment of resistance 40, or both). Once the bridge has been adiusted'turther adjustment is generally not necessary until one or the other, or both, of the tubes 24 and 26 are replaced. Aging of the tubes may, however, necessitate an occasional readiustment of the bridge.

The operationof the system will now bedescribed. Tube 24 is held at eut-oi! by the conducting condition of tube 22 when no input or framing signalis present. When a framing signal is received, however, and a negativepotential is simultaneously applied to the control electrode of the tube 22, the potential of the anode of tube 22 increases in a positive direction and thereby permits current to be drawn by tube 24. Tube 26 is normally heid non-conducting by application o! a negative potential to the control electrode of this tube through resistances 66 and 62. When neither of the tubes. are conducting, naturally the condenser 62 is electricaliy isolated from the system and receives no charging voltage. This condition exists irrespective of the position of the commutator 44-46, since if the control electrode of both of tubes 24 and 26 have applied thereto negative potentials suilicient to block the assogoo's voltage, and the position ot the commutator Iis immaterial.

It the facsimile receiver is operating at proper -speed and is in frame (proper phase) with the transmitter the commutator 44-46 closes the circuit to the anode of tube 26 prior to the time when the framing or synchronizing signal is received. The synchronizing or framing signal then conditions the bridge for operation by rendering tube 22 non-conducting and accordingly tube 24 conducting. The increased positive potential on the anode of tube 48 (due to non-conducting condition oftube 22) then permits this tube to draw current through resistance 62 and t 10- 12. Neither of the control electrodes of tubes 24 and 26 can be raised to a potential above the l potential of their cathodes due to the biasing tubes, condenser l2 cannot receive a charging 75 effect of grid current in resistances 66 and 66, respectively. Inasmuch as the potential of the control electrode of tubes 24 and 26 is fixed when the tubes are conducting the amount of current passed by each of the tubes under conducting conditions remains constant and a properly balanced condition of the bridge can be maintained,

once it is established.

At the termination of the framing or synchronizing signal tube 22 will again be permitted to draw current with the result that tube 24 is immediately biased to cut-oil'. Under conditions oi' exact proper phase relationship between the receiver and the transmitter the commutator switch 44- 46 will open the anode circuit ofY y.tube 26 exactly .at the same instant that tube 24 is rendered non-conducting. Both of the tubes 24 and 26, therefore, are rendered non-conduct= ing exactly simultaneously when the receiver is in exact synchronism and in proper phase with the transmitter. Under this condition no voltage' is produced on condenser 62 since, as described above, both of tubes 2'4 and 26 are rendered c'onducting and non-conducting exactly simultaneously.

For further explaining the operation of the' system, reference is now made to Figure 2 wherein e. series of curvesare shown. The curves are vdrawn in relation to time, and the interval from Ti to T3 corresponds to one synchronizing or framing interval which in this instance represents one line interval. Furthermore, when a single spiral helix is used this lapse of ltime from Ti to T3 also corresponds to the time required. for one revolution of the facsimile receiver printer drum. At the top oi the gure is indicated the interval at which the commutator contacts open which is marked Tr. The contacts close at the interval marked T: which corresponds. of course, to the beginning of a new interval Tr.

Under conditions when the facsimile receiver is operating in proper phase and synchronism with the transmitter the synchronizing Jmpulse.

as represented by curve 16 in Figure 2. shows the relation 'of the synchronizing impulse to the operationof the commutator contacts -,44-46,

immediately below curve 'iii are ,curves it and il which represent, respectively, the current through tubes 2c and 2d. It will be noticed that tubes 3d and 2S begin to pass current at the same instant and are both blocked or rendered non-conductive at the same instant, this latter instant corresponding to the time when the .commutator contacts open at T2. As explained above, under these conditions no charge will be placed on condenser t2 and the dotted .line shown at 'it indicates a zero charge condition for the condenser di. i

Iithe recorder or receiver is operating slow with respect to the transmitter a correction volt-v tage will then be developed on condenser d2. Under such a condition it will be assumed that the curve i9 in Figure 2 represents the received synchronizing ixnpulsepand its relation to time T2. As soon as the synchronizing impulse arrives or is received (with the commutator contacts closed) both tubes 25 and 25 are rendered conductive as explained above. Both tubes continue.

to conduct until the termination of the received synchronizing signal when tube 22 is rendered conductive and as a consequence tube 24 is rendered non-conductive. Curve ed, therefore, represents the current through tube 2d and shows the conducting period of tube 2d corresponding ,to the interval when the synchronizing or framing impulse is received. Since the recelver is running slightly slow, however, tube 26 is not simultaneously rendered non-conductive, because the commutator contacts dii-dt are not opened until a short time interral after the termination of the synchronizing impulse. During this time interval, which represents the phase diierence between the transmitter and the receiver, tube 28 continues to conduct until the commutator contacts open even though tube 2li is rendered non-conductive. During this time, the polarity across tube 4t is reversed, and condenser 56 must discharge through resistancesb before tube 28 can be biased to cut-off. The time constants of the resistance 52 and condenser ad are arranged to exceed the time occupied by one synchronizing or `framing interval. Tube de, therefore, drawsl current through condenser B2 to charge the condenser in a positive direction for the .duration of the interval between the termination of the synchronizing or framing signal and the opening of the commutator con tacts i4-4%. The current through tube t is represented by the curve 8l. while the positive charge on the condenser S is represented by the curve 82. control apparatus for' bringing about the proper desired speed and phase relationship between the receiver and transmitter.-

`The charge condition that Vexisted on condenser 52 just prior, -to'the reception oi the n synchronizing impulse is very quickly discharged as soon as both tubes 26 and 28 are rendered sents the instant that the commutator contactsl 44-48 open. In representing out-of-phase or impropei` speed conditions of the receivers with respect to the transmitter thetime interval dur- This potential vmay then be used to ing' which the synchronizing signal is received is 75 with respect to the transmitter.

conditionl both tubes 2d and 2d will be simul aesdoofa shown as shifted with respect to time Tg. The

instant the commutator contacts openjtvasl time intervals can best be represented and vis.

nalized by choosingV that instant as xed. .ac-

tually, the synchronizing or framing impulses are generally transmitted at a definite fixed rate and the operation of the commutator contacts' vary in time relation thereto-in accordance with the instantaneous speed and phase conditions oi' the receiver. Also, the time intervals T1 'and T3 are also shown fixed in Figure 2 for purposes oi simplicity, but naturally the intervals T1 and Ts vary relative to the received synchronizing impulses with variationsin Tr and, furthermore,

.the time interval between T1 and Ta (and likewise their spacing as represented in Figure. 2) will actually increase or decrease slightly if the receiver isrunning slowor fast as compared to its proper operating speed. l.

.Should the receiver be considerably out of phase and running considerably-slow with respect to the transmitter, then the condenser $2 will be charged to its maximum or full positive potential. Such a condition is represented in Figure 2 where the curve 83 represents the received synchronizing signal and its time displacement with respectl to the interval Ta. It will. be noticed that the displacement in this instance is considerably greater than the time displacement represented by the curve i9. Under such a condition of operation both tubes will be simultaneously rendered conductingas explained above, and tube 26 will be rendered non-conducting simultaneously with the termination of the scanning or framing signal as represented by the curve 8d. Tube 28, however, will continue to conduct as shown by the solid line curve until the commutator contacts open at interval Ts during which time the charge on the condenser t2 reaches a maximum. The charge on the condenser is represented by dotted curve dd.

If, however, the receiver or recorder is operating fast with respect tothe transmitter, then a dierent operation of the bridge circuit taires place. The curve shown at d? represents, for example. a slight advancement of the recorder Under such taneously rendered conducting; however, the conductive condition of tube 2d will be terminated while the synchronizing impulse is still being received by reason of the operation of the commutator contacts di-d6. The curve d@ shows, therefore, the time interval during which the tube 2t will be permitted to pass current, which interval is lessthan the interval occupied by the synchronizing signal. Tube 2d, however, will continue to conduct until the scanning synchronizing or framing signal has terminated.

Curve t9, therefore, shows a curve representing` the current through jtube 25. Since tube 2t is rendered non-conducting by the operation of the commutator, prior to the discontinuance of op eration of tube 2d, a charge will be placed on condenser 62 in a negative direction, as indicated by the curve 9d. It will Abe noticed that this charge is negative under -a condition when .the receiver is operating fast with respect to the transmitter, whereas in the above assumed ex'- ample where the receiver was operating slower than the transmitter a positive charge was produced on the condenser.

If the receiver is appreciably faster and considerably more out oi' phase with respect to the transmitter then a still diierent setl of circumstances exist. Under these conditions it will beA assumed thatthe commutator contacts M open prior to the reception of thesynchronizing impulse, as shown by curve 9|. Under this condition tube 26 is not rendered conducting, but instead only tube 24 is rendered conducting and its conducting condition exists during the time of .reception of the synchronizing' signal. VThe period of conductivity of the tube 24 is represented by the curve l2. Under such a condition a stronger negative charge will be placed on condenser 62, as represented by the curve S3.

It will be seen, therefore, that a potential may be derived from the terminals 10--12 having a polarity depending upon whether the receiver is slow or fast with respect to the transmitter. 'Furthermore, it may be seen 'that the intensity of the potential or its magnitude is a function of the out-of-ph'ase relationship between the receiver and the transmitter.

The polarity of the Aproduced control potential will be in accordance with the nearest framing condition. Framing, therefore, will take place in the direction requiring the least amount of time,

since the bridge circuit can produce either positive or negative control voltages. For example, should the receiver for some reason begin to run fast and ilnaliy reach a phase condition so that it is more'than 180 degrees fast with respect to the transmitter, the then produced control potential will not operate to slow down the receiver but will instead continue to increase the speed of the e receiver until :the proper phase operating condition is reached. since it would require a lesser amount of time to frame the retube 26 will remain conducting. as indicated by curve It to thereby place a positivecharge on the condenser 62, as indicated by the curve 91.

With the system so far described and without the inclusionof the condenser 68 and resistance Il, first order correction potentials will be produced across condenser i2., The additional fea'- ture of the system, however, includes the network of the resistance 64 and condenser 86 which are placed across the condenser 62. These elements permit second order correction to be obtained. As explained above the addition of the second order correction adds greatly to the accuracy of synchronism. The operation of the ceiver in that direction than in the opposite.

This is a distinct advantage over the prior art synchronizing systems where, framing is always A in the slow direction. As a result of the ad- Such a condition is represented by thecurve 94 shows-the received synchronizing slgl nals,l occurring at time intervals T1 and T: and

approximately 180 degrees out of phase with respect to the transmitter. As long as the receiver synchronizing signal overlaps to any extent the interval during which the commutator contacts L M are closed, then the receiver or I 4 recorder will frame in the fast direction. How.

ever, if there is noov'erlappins` the framing will be in the slow direction. Curve Il shows a slight overlapping of the received synchronizing signal with they interval during which the commutator contacts are closed and under this condition tube 24 will be first rendered conductive as represented by the curve il, while tube Il remains non-conductive. During this slight time interval a negative charge will begin to develop on condenser !2, but as soon as the commutator contacts close (during which time the synchronizing signal is still being received, as indicated by curve 94), tube- 26 will also be rendered conriucive,` and as long as both tubes are conducting ne further charge will be deposited on the condenser but instead condenser i2 will be discharged. As soon as the synchronizing signal terminates, however, tube 2l will be rendered non-conductive, as indicated by curve il, while @denser 68 had no initial charge).

second order correction network is as follows:

It will be assumed that the value of the resistance 6I is.oi such value that condensers 82 and 66 will equalize to a ilxed voltage in a time interval less 'than that represented by T1 and Ts. Then if the value of the condensers 82 and M are equal, the voltage available at the output terminals 1I--12 will be divided according to the position of theV movable contact 63 along with the potentiometer resistance il. Ii' the movable contact is at or near the center of the resistance 64 the result then isto obtain at the output terminals a potential equivalent to one-half the potential initially deposited on condenser 62 by the first framing impulse. Since condenser 82 is electrically isolated as soon as the synchronizing signal terminates, the charge on condenser B2 equalizes so that condensers 88 and 62 nally assume a charge equal to one-half the total charge or original charge on 82 (assuming conl During this equalizing interval the voltage available at the output terminals 'ill-1! remains constant by reason of the inclusion of the potentiometer 84 and the position of the .contact 68 at the center thereof. 'I'hel next framing impulse recharges condenser 62 to some new value, and theloutput potential will then be the average of the charges then existing on condensers 62 and 68. This charge condition will then equalize to a new value during the following line` interval. Accordingly, each time a signal framing impulse changes the charge on condenser 82 up cr down the previous charge on condenser is also slightly altered and is also effective toward controlling the po-` tential available at the output terminals. v

If for example, 2E1 represents the first charge on condenser l2, 2E: the second charge, and so forth. then: f

lst order correction2E|=El Inasmuch as the smalleriraction'values of El are not of greater magnitude corrections beyond'the second order are `not'ordinarily necescondenser 66 it may, therefore, be seen th'atby providing `second order control a decided. im-

provement is made in synchronizing facsimile receivers with transmitters.

`on condenser S2 when the recorder is operating only slightly slow and fast, respectively, show a charge of a predetermined value at the end of the charging period. This charge then reduces to a lesser value, as shown in the curves, due to the equalization of the charge between condensers di? and 66 (for second order storage). In curves dt and 93 there is no reduction in charge following the charging period since the charging period is of sumcient duration to permit both condensers d2 and @d to reach maximum charge condition. Full'correction potential is, therefore, available at terminals lel2 when the receiver is appreciably slow or fast.

The produced potential available at terminals 'iu-'l2 may be conveniently used for controlling the speed or phase or operation of the facsimile receiver printer drum and various circuits or elements may be used that are responsive to this potential for bringing about the desired result. Ii', for example, the recorder is driven by a. synchronous motor the potentiel as well as its polarity may be used to control the frequency of the supply voltage to thereby cause the receiver to increase or retard its speed to bring about the desired phase relationship. if, on the other hand, the receiver is driven by an induction motor the regulation of the receiver may still m accomplished by controlling the frequency applied to the motor or if this is not done the speed may also be altered by increasing or decreasing the voltage applied to the induction motor to thereby increase or decrease the speed ot'. the motor. if the `facsimile receiver drum is-driven by an d. C.

and/or D. C. series vconunutating motor or by a direct current shunt motor, the speed oi the motor may be regulated byv the voltage applied to the motor. by varying the held strength oi the direct current shunt motor, or by regulating a brakingaction on the motor regardless oi type. Since the control potential produced by the present invention and available at 'it-72 may have one polarity or another, and since it varies in intensity,.such a potential may be used ior concharge paths, means responsive to the produced negative control impulses for varying the oonductlvity of one of the discharge paths between the limits of zero and a i'flnite value, a facsimile receiver printer drum, switching means essociated with said drum to intermittently apply an s operating potential to the other of said paths to condition said path for. conduction, means responsive to the produced negative control irnpulses to render said other path conducting when an operating potential is applied thereto by said switching means, means for maintaining conductivity to said other path irrespective of the continued conductive condition of said one path and irrespective of the continued presence oithe negative control yimpulse until said switching means removes the` voperating potential. and a condenser associated with said discharge paths and connected between the junction of said discharge paths and a point of fired potential in said bridge arrangement wlhereby a charge potential will be deposited on said condenser in a polarity determined by the direction of phase dis,- placement between the operation of the switching means and the received synchronizing impulses, the intensity of the charge potential being a function of the degree of phase displacement.

2. A facsimile receiving system such as defined i in claim l wherein said condenser has connected in parallel therewith the series combination oi a resistance and a second condenser whereby a portion of the charge produced on said first condfi trolling the driving medium tor the facsimile receiver irrespective of what medium is used.

Inasmuch as the present invention is concerned with the production of speed regulation control potentials, the facsimile receiver proper fili has not been shown, since it will be appreciated by those skilled i/zi/f` the art that any desirable facsimile receiver'may used.

. It is to be understood that the use of the terms I pictures or picture signals ls meant to include the transmission of views, printed matter, checks, ringer prints, photographs, weather and military or other type maps, nanclal statements. articles, advertisements. `fashion plates, magazine articles, moving pictures, and the like, and, in fact, all types ci subjects wherein a visual representation of the subject matter transmitted is to be reproduced at a receiving point.

denser when an out-oi-phase relationship exists will be transferred to said second condenser and retain thereby through said next succeeding charging interval, and output terminals connected to the common electrode of said condensers and to a point along said resistance whereby a correction potential `may be derived from said terminals.

3. A facsimilerecelving system for receiving picture and framing impulses, the picture signals being representative of a subject matter scanned and the framing impulses occurring at regularly spaced intervals, comp means responsive to the received fr ism-t impulses to produce corresponding control impulses, a bridge arrangement including a pair oi sexies-connected electron discharge paths, means ve to the produced control impulses i'or 1- the conductivity of one of the discharge paths between predetermined substantiallv lined limits, a facsimile receiver printer drum, commutator means associated with said printer drum to intermittently apply an operating potential to the other of said paths to condition said path .for conduction, means responsive to the produced control impulses to render said other path conducting when Various alterations and mentions may be made in the present invention without departing from the spirit and scope thereof, and Iit is desired that any and all such modifications be considered within the ew of the present invention, except 'as limited by the here appended an operating potential is applied thereto by said commutator means, means i'or maintaining conductivity of said other path irrespective of the continued presence of the control impulse until said contator `means removes the operating potential, and an eltron stoe device connected between the Junction oi said series con- `with said drum to intermittently apply an opernected discharge paths and a point o f fixed potential in said bridge arrangement whereby a charge will be produced on said electron storage device having a polarity determined by the time sequence between .the received framingY impulses and the operation of the commutator means, the nagnitude of the produced charge boing a function of the degree of'time differencef 4. A facsimile receiving system for receiving picture and synchronizing impulses, the picture signals representing, a scanned subject matter and the synchronizing impulses related thereto occurring at regularly spaced intervals, comprising a bridge arrangement including a pair of ries-connected electron discharge paths, means responsive to the received synchronizing impulses for controlling the conductivity of one of the discharge paths between predetermined limits, a facsimile receiver printer drum, means associated ating potential to the other of said paths to condition said path for conduction, means responsive to the received synchronizing impulses to render said other path conducting when said path is conditioned for conduction, means for maintaining established conductivity of said other path as long as an operating potential is applied thereto the received synchronizing impulses to produce corresponding negative control impulses, a fac- `simile receiver printer drum., switching means .associated with said drum for opening and 'ciosing an electric circuitl a bridge arrangement including a pair of electron discharge tubes conframing impulses and to the operation of said commutator means .for causing said tubes to be simultaneously rendered conductingY and nonconducting when the facsimile receiver is in lproper phase and is operating in synchronism with received framing impulses, and means to place a potential charge on said condenser-when the facsimile receiver is out of phase with the lreceived framing impulses, the polarity of the charge being determined in accordance with the direction of phase displacement and the magnitude of the charge being determined in accord-l ance with the degree of phase displacement. l

'7. A facsimile receiver such as defined in claim 6 wherein said condenser is relieved of its charge each time a framing impulse is received, said condenser having connected in parallel therewith the series combinationof a resistance and an.

electron storage element whereby a charge will' be placed on said electron storage element from said condenser. the charge on lsaid electron Stor--` ling a subject matter scanned and the framing impulses occurringat regularly spaced intervals. comprising a facsimile-` receiver printer drum,

commutator means associated with said printer drum, a circuit-arrangement including a pair of series-connected electron discharge paths, an

nected in series, a condenser in said bridge circuit associated with Isaid tubes and connected i between the junction of said tubes and a point of 'xed potential, means responsive to the produced negative control impulses and to the operation of said switching means for causing said tubes to be simultaneously rendered conducting and non-conducting when the facsimile receiver is in proper phase and is operating in synchronism with received synchronizing impulses, and means to place a 'potential-charge on said condenser when the facsimile receiver is out of phase and synchronism with the received synchronizing impulses, the polarity of the charge being determined in accordancewiththe directon nf phase displacement and the intensity of the charge being determined in accordance with the degree of phase displacement and lack of synchronism.

'6. A facsimile receiver for receiving picture and framing impulses, the picture signals representing asubject matter scanned and the framing impulses-occurring at uniformly spaced intervals, comprising a facsimile receiver printer drum, commutator means associated with said electron storage element in said circuit associated with said discharge paths,` and means responsive to the received framing impulsesand to the operation of said commutator means for causing said electron paths to be rendered conducting and non-conducting to place a potential chargeon said electron storage element when the facsimile receiver is out of phasewith the received framing impulses, the polarity of the charge being determined in accordance with the direction of phase displacement and the magnitude of the charge being determined in accordance with the degree of phasev displacement.

9. A facsimile receiving system such as defined in claim 8 wherein said electron storage element has connected in parallel therewith the series combination `of a resistance and a second electron storage element, and output terminals connected between the common terminals of the electron storage elements and a point along said resistance.

10. A facsimile receiving system for receiving picture and synchronizing impulses, the picture signals being representative of asub'ject matter scanned at a transmitter and the synchronizing impulses occurring at regularly spaced intervals,

comprising a facsimile receiver printer drum,

switching means associated with said drum and operating in synchronism and phasetherewith.

a condenser, and circuit means including a pair of electron discharge tubesresponsive to the received synchronizing impulses and to the operation of saidswitching means for placing a podrum, a bridge arrangement including a pairof electron discharge tubes'connected in series'. a condenser in said bridge circuit cojnnecte'i between the junction of said tubes and a point nf fixed potential, means responsive to the received teutial charge on said condenser when a time interval exists between the termination of the received synchronizing impulses and the operation of said lswitching means, said circuit means operating to piace a positive charge on said condenser when the synchronizing impulses terminate prior to the operation of said switching means and a negative charge on said condenser 'picture and synchronizing or framing impulses,

the picture signals being representative of a subject matter scanned at a transmitterv and the related framing impulses occurring at uniformly spaced intervals, comprising a 'facsimile receiver f printer drum, commutating means associated with said printer drum and operating in synchronism and phase therewith, an electron storage element, and circuit means jointly'responsive to the received framing impulses and to the operation of said commutating means for placing a potential charge on said electron storage element when an out-of-phase relationship exists between the termination of the framing impulses and the operation of said commutating means, said means operating to place a charge of one polarity on said electron storage element when vthe framing impulses conclude prior to the operation of said commutatingv means and a charge of opposite polarity on said electron storage element when the framing impulses continue to be received after Aoperation of said commutating means, the magnitude ofthe charge being determined by the eittent of the out-of-phase relationship.

`13. A facsimile receiving system such as defined in claim 12 wherein said electron storage element has connected in parallel therewith the series combination of a resistance and asecond electron storage element whereby a portion of the charge produced on said rst electron storage element when an out-of-phase relationship exists will be transferred to said second electron storage element and retain thereby through said next succeeding charging'interval point along said resistance whereby a correction potential may be derived irom said terminals.

14. A facsimile receiving system for receiving picture and synchronizing or framing impulses, the picture signals being representative oi a subject matter scanned at a transmitter andthe related training impulses occurring at regularly spaced intervals,.comprising a facsimile receiver printer mechanism, circuit controlling means associated with said mechanism 'and operating in synchronism and phase therewith, an electron storage element, and means jointly responsive to the received framing impulses and to the operation of said circuit controlling means for placing a potential chargey on said electron storage elei ment when a time interval exists between the' termination of the received framing impulse and the operation ofA said circuit controlling means, the polarity of the charge placed on said electron storage element being determined by the time sequence' of the receipt of the framing impulse as compared with the operation of said circuit ccntrollng means, the intensity ofthe charge being determined by the extent of the time interval.

- 15. A, facsimile receiver such as defined in L claim 1s wherein said electron storage element is relieved of its charge each time a framing impulse is received, said element having connected in parallel therewith the series combination of a resistance and a seco-nd electronv storage element the charge deposited on said second electron storage element from said rst element being retained during'receipt of framing impulses.

16. A facsimile receiving system for receiving picture and synchronizing or framing impulses, the picture signals being representative of a subject matter scanned at a transmitter and the related synchronizing impulses occurring at regularly spaced intervals, comprising a facsimile receiver printer drum, switching means associated with said drum and operating in synchronism and phase therewith, a condenser, and means responsive to the received synchronizing impulses and to the operation of said switching means' for placing a charge on said condenser when a time interval exists between the termination of the received synchronizing impulses and the operation of said switching means, the polarity of the chargeI potential being determined by the time relationship of the termination of the synchronizing impulses as compared to the operation of the said switching means and the intensity of the charge being determined by the time diierential.

i7. A facsimile receiving system for receiving picture and synchronizing or framing impulses', the picture signals being representative of a subject matter scanned at a transmitter and thev related framing impulses occurring at evenly spaced time intervals, comprising a facsimile receiver printer drum, commutator means associated with said drum and operating in synchronism and phase therewith, an electron storage element, and means jointly responsive to the re- 'ceived framing impulses and to the operation of said commutator means for placing a potential charge on said electron storage velement when e.'

time interval exists between the termination of the received framing impulses and the operation of said commutator means, the polarity of the charge being determined by the time relationship between the termination of the framing impulses and the operation of the said commutator means and the magnitude of the charge beingdetermined by the time diderential.

la. A facsimile receiver such as sieined in claim l7 wherein said electron storage element is relieved of its charge each time a framing impulse is received, said electron storage element having connected in parallel therewith the series combination of a resistance and a second electron storage element whereby the latter element may be Vcharged bysaid first element, the charge on said second electron storage element, being retained during receipt of framing impulses. and output terminals connected to a point along said resistance and to the common terminal of said l electron storage elements.

19. A facsimile receiving system for receiving picture and synchronizing or framing impulses. the picture signals being representative of a subject matter scanned at a transmitter and the related irarning impulses occurring at regularly spaced intervals, comprising a facsimile receiver mechanism, circuit controlling means associated with said mechanism and operating in synchronism and phase therewith, an electron storage element, means responsive to both the received framing impulses and the operation of the circuit controlling means for placing a potential charge on said electron storage element when a time interval exists between the received framing impulses and the operation of said circuit controlling means, the polarity of the charge being deter1 mined by' the time relationship of the received 20. A facsimile receiving system for receiving picture and synchronizing or framing impulses. the picture signals being representative ot a subject matter scanned at a transmitter and the re` lated framing impulses occurring at regularly spaced intervals, comprising a facsimile receiver mechanism, circuit controlling means associated with'said mechanism'and operating in synchronism and phase therewith. an electron storage eleing impulses and the operation ofthe circuitccnytrolling means for placing a potential charge on ment, means responsive to both the received i'ram- 20 said electron storage element when a time intervalexists between the received framing impulses and the operation of said circuit4 controlling means, the polarity of-the charge being determined by the time relationship o'i the received framing impulses as compared with the operation of thevsaid circuit controlling means and the magnitude of the charge being determined by the time diii'erential, said electron storage element having connected in parallel therewith the series combination ot a resistance and a second electron storage element whereby; a portion oi' the charge produced on said ilrst electron storage element when time interval exists will be transferred to said second electron storage element and retain thereby through said next succeeding iraming impulse charging interval.

` MAURICE ARTZT. 

